# Frame for bicycle

A frame for a bicycle includes a front frame, a rear frame, an upper linkage, and a shock absorber. The rear frame is pivoted to the front frame at a main pivot axis. The upper linkage is pivoted to the front frame at a first pivot axis and is pivoted to the rear frame at a second pivot axis. The shock absorber is pivoted to the upper linkage at a third pivot axis and is pivoted to the front frame. When a compression ratio of the shock absorber is in a range between 0% and 60%, a distance variation between a pivot location of the rear frame at the second pivot axis and a pivot location of the rear frame at the main pivot axis reaches a maximum value thereof.

## Latest Giant Manufacturing Co., Ltd. Patents:

**Description**

**CROSS-REFERENCE TO RELATED APPLICATION**

This application claims the priority benefit of Taiwan application serial no. 106127988, filed on Aug. 17, 2017. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

**BACKGROUND OF THE INVENTION**

**Field of the Invention**

The invention relates to a frame for a bicycle, and in particular, to a frame for a bicycle having a shock-absorbing function.

**Description of Related Art**

To adapt to rugged road surfaces, a frame for a bicycle may be integrated with a shock absorber to provide adequate buffering. To integrate the shock absorber with the frame, it is required to design a plurality of pivots on the frame. However, during the shock absorbing process, it is difficult to avoid deformation of the frame. As time passes, fatigue of the frame is increased, and a lifetime of the frame is thus reduced.

**SUMMARY OF THE INVENTION**

The invention provides a frame for a bicycle for reducing fatigue of the frame and thereby enhancing a lifetime of the frame.

The frame for a bicycle of the invention includes a front frame, a rear frame, an upper linkage, and a shock absorber. The rear frame is pivoted to the front frame at a main pivot axis. The upper linkage is pivoted to the front frame at a first pivot axis and is pivoted to the rear frame at a second pivot axis. The shock absorber is pivoted to the upper linkage at a third pivot axis and is pivoted to the front frame. When a compression ratio of the shock absorber is 0%, a distance variation between a pivot location of the rear frame at the second pivot axis and a pivot location of the rear frame at the main pivot axis is 0. When the compression ratio of the shock absorber is in a range between 0% and 60%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches a maximum value thereof.

In an embodiment of the invention, the shock absorber is pivoted to the front frame at the main pivot axis.

In an embodiment of the invention, the front frame includes a seat tube and a down tube, the rear frame includes a seat stay and a chain stay, the seat stay is fixed to the chain stay at a rear wheel center, the chain stay is pivoted to the down tube at the main pivot axis, the upper linkage is pivoted to the seat tube at the first pivot axis and is pivoted to the seat stay at the second pivot axis, the shock absorber is pivoted to the down tube, when the compression ratio of the shock absorber is 0%, a distance variation between a pivot location of the seat stay at the second pivot axis and a pivot location of the chain stay at the main pivot axis is 0, and when the compression ratio of the shock absorber is in the range between 0% and 60%, the distance variation between the pivot location of the seat stay at the second pivot axis and the pivot location of the chain stay at the main pivot axis reaches a maximum value thereof.

In an embodiment of the invention, the shock absorber is pivoted to the down tube at the main pivot axis.

In an embodiment of the invention, when the compression ratio of the shock absorber is in a range between 40% and 60%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof.

In an embodiment of the invention, when the compression ratio of the shock absorber is in a range between 45% and 55%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof.

In an embodiment of the invention, when the compression ratio of the shock absorber is 50%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof.

In an embodiment of the invention, when the compression ratio of the shock absorber is 0%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis is 0.

In an embodiment of the invention, when the compression ratio of the shock absorber is 100%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis is 0.

In an embodiment of the invention, when the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof, projections of the main pivot axis, the first pivot axis, and the second pivot axis on a geometric plane are located on a same straight line.

In an embodiment of the invention, a distance between the pivot location of the rear frame at the main pivot axis and the pivot location of the rear frame at the second pivot axis is equal to a distance between projections of the main pivot axis and the second pivot axis on a geometric plane, a distance between projections of the main pivot axis and the second pivot axis on the geometric plane is a first distance when the compression ratio of the shock absorber is 0%, a distance between projections of the main pivot axis and the second pivot axis on the geometric plane is a second distance when the shock absorber is compressed and projections of the main pivot axis, the first pivot axis and the second pivot axis on the geometric plane located on a same straight line, and the second distance minus the first distance is less than 4 mm.

In an embodiment of the invention, a distance between projections of the main pivot axis and the second pivot axis on a geometric plane under the compression ratio of the shock absorber is 60% is less than a distance between projections of the main pivot axis and the second pivot on the geometric plane under the compression ratio of the shock absorber is 35%.

In light of the above, in the invention, the compression ratio of the shock absorber is set by configuring the distance variation of the rear frame at the first pivot axis and the second pivot axis to reach the maximum value thereof, so as to reduce fatigue of the frame and thereby enhance the lifetime of the frame.

To provide a further understanding of the aforementioned and other features and advantages of the disclosure, exemplary embodiments, together with the reference drawings, are described in detail below.

**BRIEF DESCRIPTION OF THE DRAWINGS**

**DESCRIPTION OF THE EMBODIMENTS**

Referring to **100** for a bicycle includes a front frame **110**, a rear frame **120**, an upper linkage **130**, and a shock absorber **140**. The rear frame **120** is pivoted to the front frame **110** at a main pivot axis A**0**. The upper linkage **130** is pivoted to the front frame **110** at a first pivot axis A**1** and is pivoted to the rear frame **120** at a second pivot axis A**2**. The shock absorber **140** is pivoted to the upper linkage **130** at a third pivot axis A**3** and is pivoted to the front frame **110**. When a compression ratio of the shock absorber **140** is 0%, a distance variation between a pivot location of the rear frame **120** at the second pivot axis A**2** and a pivot location of the rear frame **120** at the main pivot axis A**0** is 0. When the compression ratio of the shock absorber **140** is in a range between 0% and 60%, the distance variation between the pivot location of the rear frame **120** at the second pivot axis A**2** and the pivot location of the rear frame **120** at the main pivot axis A**0** reaches a maximum value thereof.

It is noted that when the compression ratio of the shock absorber **140** exceeds 60%, the rear frame **120** is subject to a greater force. At this time, if a deformation of the rear frame **120** (i.e., the distance variation between the pivot location of the rear frame **120** at the second pivot axis A**2** and the pivot location of the rear frame **120** at the main pivot axis A**0**) also reaches a maximum value thereof, the rear frame **120** may be damaged. Therefore, in the present embodiment, when the compression ratio of the shock absorber **140** is in the range between 0% and 60%, the deformation of the rear frame **120** (i.e., the distance variation between the pivot location of the rear frame **120** at the second pivot axis A**2** and the pivot location of the rear frame **120** at the main pivot axis A**0**) already reaches the maximum value thereof, so fatigue of the frame **100** (especially the rear frame **120**) can be reduced to enhance a lifetime of the frame **100**.

Referring to **110** includes a seat tube **112** and a down tube **114**. The rear frame **120** includes a seat stay **122** and a chain stay **124**. The seat stay **122** is fixed to the chain stay **124** at a rear wheel center Cr, and the chain stay **124** is pivoted to the down tube **114** at the main pivot axis A**0**. The upper linkage **130** is pivoted to the seat tube **112** at the first pivot axis A**1** and is pivoted to the seat stay **122** at the second pivot axis A**2**. The shock absorber **140** is pivoted to the upper linkage **130** at the third pivot axis A**3** and is pivoted to the down tube **114**.

Referring to **140** may be pivoted to the front frame **110** at the main pivot axis A**0**. Specifically, the shock absorber **140** may be pivoted to the down tube **114** of the front frame **110** at the main pivot axis A**0**. Since the shock absorber **140** is pivoted at the main pivot axis A**0** where the rear frame **110** is also pivoted, the structure of the frame **100** can be made simpler.

Referring to **140** is not compressed (namely, when the compression ratio of the shock absorber **140** is 0%), a distance variation between a pivot location of the seat stay **122** at the second pivot axis A**2** and a pivot location of the chain stay **124** at the main pivot axis A**0** is 0.

Referring to **140** is being compressed (namely, when the compression ratio of the shock absorber **140** is in the range between 0% and 60%), the distance variation between the pivot location of the seat stay **122** at the second pivot axis A**2** and the pivot location of the chain stay **124** at the main pivot axis A**0** is increased to a maximum value Vmax thereof (e.g., 4 mm).

Referring to **140** is fully compressed (namely, when the compression ratio of the shock absorber **140** is 100%), the distance variation between the pivot location of the seat stay **122** at the second pivot axis A**2** and the pivot location of the chain stay **124** at the main pivot axis A**0** is reduced to extremely close to 0. In another embodiment, the distance variation may also be reduced to 0.

In the present embodiment, as shown in **140** increases from 0% to 100%, the distance variation between the pivot location of the seat stay **122** at the second pivot axis A**2** and the pivot location of the chain stay **124** at the main pivot axis A**0** first increases and then decreases, namely, in a way similar to a tendency of an arc line bending upwards. When the compression ratio of the shock absorber **140** is 0%, the distance variation between the pivot location of the seat stay **122** at the second pivot axis A**2** and the pivot location of the chain stay **124** at the main pivot axis A**0** is 0. When the compression ratio of the shock absorber **140** is 100%, the distance variation between the pivot location of the seat stay **122** at the second pivot axis A**2** and the pivot location of the chain stay **124** at the main pivot axis A**0** is 0 or extremely close to 0.

In the present embodiment, when the compression ratio of the shock absorber **140** is in the range between 0% and 60%, the distance variation between the pivot location of the rear frame **120** (i.e., the seat stay **122**) at the second pivot axis A**2** and the pivot location of the rear frame **120** (i.e., the chain stay **124**) at the main pivot axis A**0** reaches the maximum value Vmax thereof.

In another embodiment, when the compression ratio of the shock absorber **140** is in a range between 40% and 60%, the distance variation between the pivot location of the rear frame **120** (i.e., the seat stay **122**) at the second pivot axis A**2** and the pivot location of the rear frame **120** (i.e., the chain stay **124**) at the main pivot axis A**0** reaches the maximum value Vmax thereof.

In another embodiment, when the compression ratio of the shock absorber **140** is in a range between 45% and 55%, the distance variation between the pivot location of the rear frame **120** (i.e., the seat stay **122**) at the second pivot axis A**2** and the pivot location of the rear frame **120** (i.e., the chain stay **124**) at the main pivot axis A**0** reaches the maximum value Vmax thereof.

In another embodiment, when the compression ratio of the shock absorber **140** is 50%, the distance variation between the pivot location of the rear frame **120** (i.e., the seat stay **122**) at the second pivot axis A**2** and the pivot location of the rear frame **120** (i.e., the chain stay **124**) at the main pivot axis A**0** reaches the maximum value Vmax thereof.

In the present embodiment, as shown in **120** (i.e., the seat stay **122**) at the second pivot axis A**2** and the pivot location of the rear frame **120** (i.e., the chain stay **124**) at the main pivot axis A**0** reaches the maximum value Vmax thereof, the main pivot axis A**0**, the first pivot axis A**1**, and the second pivot axis A**2** may be located on the same geometric plane P. In other words, when the distance variation between the pivot location of the rear frame **120** (i.e., the seat stay **122**) at the second pivot axis A**2** and the pivot location of the rear frame **120** (i.e., the chain stay **124**) at the main pivot axis A**0** reaches the maximum value Vmax thereof, projections of the main pivot axis A**0**, the first pivot axis A**1**, and the second pivot axis A**2** on another geometric plane Q different from the geometric plane P may be located on the same straight line L. For example, this geometric plane Q is a geometric plane on which the drawing sheet is located. Alternatively, this geometric plane Q may be located on a geometric plane formed by a forward direction Df and a gravity direction Dg, wherein the forward direction Df refers to a direction in which a bicycle adopting the frame **100** travels forward, and the gravity direction Dg refers to a direction of the gravity force to which the bicycle adopting the frame **100** is subjected. Moreover, this geometric plane Q may also be a geometric plane on which the front frame **110** is located.

Referring to **120** (i.e., the seat stay **122**) at the main pivot axis A**0** and the pivot location of the rear frame **120** (i.e., the chain stay **124**) at the second pivot axis A**2** may be equal to the main pivot axis A**0** and the second axis A**2** is equal to a distance d between projections of the main pivot axis A**0** and the second pivot axis A**2** on the geometric plane Q. A distance between projections of the main pivot axis A**0** and the second pivot axis A**2** on the geometric plane Q is a first distance when the compression ratio of the shock absorber **140** is 0%. A distance between projections of the main pivot axis A**0** and the second pivot axis A**2** on the geometric plane Q is a second distance when the shock absorber **140** is compressed and projections of the main pivot axis A**0**, the first pivot axis and the second pivot axis A**2** on the geometric plane Q located on the same straight line L. The second distance minus the first distance is less than 4 mm.

Referring to **0** and the second pivot axis A**2** on a geometric plane Q under the compression ratio of the shock absorber **140** is 60% may be less than a distance between projections of the main pivot axis A**0** and the second pivot A**2** on the geometric plane Q under the compression ratio of the shock absorber **140** is 35%.

Referring to **140**, the required force becomes greater and greater. If the maximum deformation of the frame (i.e., the maximum distance variation) occurs in the rear stage of the compression ration of the shock absorber **140**, large forces and large deformations will significantly shorten the life of the frame. Therefore, the maximum value Vmax of the distance variation can be set in the front stage (i.e., 0% to 60%) of the compression ratio of the shock absorber **140**, which helps to extend the frame life. In addition, the maximum value Vmax of the distance variation falls on 50% of the compression ratio of the shock absorber **140**, which contributes to the balance of both sides of the relationship curve, so that the maximum value of the distance variation can be made lower.

In summary of the above, in the invention, the compression ratio of the shock absorber is set by configuring the distance variation of the rear frame at the first pivot axis and the second pivot axis to reach the maximum value thereof, so as to reduce fatigue of the frame and thereby enhance the lifetime of the frame.

Although the invention is disclosed as the embodiments above, the embodiments are not meant to limit the invention. Any person skilled in the art may make slight modifications and variations without departing from the spirit and scope of the invention. Therefore, the protection scope of the invention shall be defined by the claims attached below.

## Claims

1. A frame for a bicycle comprising:

- a front frame;

- a rear frame pivoted to the front frame at a main pivot axis;

- an upper linkage pivoted to the front frame at a first pivot axis and pivoted to the rear frame at a second pivot axis; and

- a shock absorber pivoted to the upper linkage at a third pivot axis and pivoted to the front frame, wherein when a compression ratio of the shock absorber is in a range between 0% and 60%, a distance variation between a pivot location of the rear frame at the second pivot axis and a pivot location of the rear frame at the main pivot axis reaches a maximum value thereof.

2. The frame for a bicycle according to claim 1, wherein the shock absorber is pivoted to the front frame at the main pivot axis.

3. The frame for a bicycle according to claim 1, wherein the front frame comprises a seat tube and a down tube, the rear frame comprises a seat stay and a chain stay, the seat stay is fixed to the chain stay at a rear wheel center, the chain stay is pivoted to the down tube at the main pivot axis, the upper linkage is pivoted to the seat tube at the first pivot axis and is pivoted to the seat stay at the second pivot axis, the shock absorber is pivoted to the down tube, and when the compression ratio of the shock absorber is in the range between 0% and 60%, a distance variation between a pivot location of the seat stay at the second pivot axis and a pivot location of the chain stay at the main pivot axis reaches a maximum value thereof.

4. The frame for a bicycle according to claim 3, wherein the shock absorber is pivoted to the down tube at the main pivot axis.

5. The frame for a bicycle according to claim 1, wherein when the compression ratio of the shock absorber is in a range between 40% and 60%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof.

6. The frame for a bicycle according to claim 1, wherein when the compression ratio of the shock absorber is in a range between 45% and 55%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof.

7. The frame for a bicycle according to claim 1, wherein when the compression ratio of the shock absorber is 50%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof.

8. The frame for a bicycle according to claim 1, wherein when the compression ratio of the shock absorber is 0%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis is 0.

9. The frame for a bicycle according to claim 8, wherein when the compression ratio of the shock absorber is 100%, the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis is 0.

10. The frame for a bicycle according to claim 1, wherein when the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof, the main pivot axis, the first pivot axis, and the second pivot axis are located on a same geometric plane.

11. The frame for a bicycle according to claim 1, wherein when the distance variation between the pivot location of the rear frame at the second pivot axis and the pivot location of the rear frame at the main pivot axis reaches the maximum value thereof, projections of the main pivot axis, the first pivot axis, and the second pivot axis on a geometric plane are located on a same straight line.

12. The frame for a bicycle according to claim 1, wherein a distance between the pivot location of the rear frame at the main pivot axis and the pivot location of the rear frame at the second pivot axis is equal to a distance between projections of the main pivot axis and the second pivot axis on a geometric plane, the distance between projections of the main pivot axis and the second pivot axis on the geometric plane is a first distance when the compression ratio of the shock absorber is 0%, the distance between projections of the main pivot axis and the second pivot axis on the geometric plane is a second distance when the shock absorber is compressed and projections of the main pivot axis, the first pivot axis and the second pivot axis on the geometric plane located on a same straight line, and the second distance minus the first distance is less than 4 mm.

13. The frame for a bicycle according to claim 1, wherein a distance between projections of the main pivot axis and the second pivot axis on a geometric plane under the compression ratio of the shock absorber at 60% is less than the distance between projections of the main pivot axis and the second pivot axis on the geometric plane under the compression ratio of the shock absorber at 35%.

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**Patent History**

**Patent number**: 10814932

**Type:**Grant

**Filed**: Jun 28, 2018

**Date of Patent**: Oct 27, 2020

**Patent Publication Number**: 20190054974

**Assignee**: Giant Manufacturing Co., Ltd. (Taichung)

**Inventors**: Ching-Sung Yi (Taichung), Shao-Chieh Liu (Taichung), Tzu-Pin Wu (Taichung)

**Primary Examiner**: Tony H Winner

**Application Number**: 16/021,033

**Classifications**

**Current U.S. Class**:

**Yielding (280/283)**

**International Classification**: B62K 25/28 (20060101); B62K 3/02 (20060101);